Field of the Invention
The present invention relates to a ranging apparatus and a moving object, and more particularly to a ranging apparatus and a moving object which are capable of performing high-accuracy ranging by an imaging plane phase difference method.
Description of the Related Art
To assist the movement of a moving object, such as a vehicle, a drone, or a robot, it is required to measure a distance between a moving object, and an object, such as an obstacle, around the moving object. Particularly, to assist the movement of the moving object e.g. for avoiding collision or for tracking another object, it is also required to perform recognition processing using images of an obstacle, and hence, a camera as an image pickup apparatus is often used in the moving object, for measuring a distance to the obstacle. As a method of acquiring not only images but also distances using a camera, there has been known an imaging plane phase difference method (Japanese Laid-Open Patent Publication (Kokai) No. 2013-190622). In the imaging plane phase difference method, parallax between a pair of images formed by light fluxes having passed through two different regions (partial pupils) of an exit pupil of an optical system of the camera is determined, and distance information (phase difference of image signals) of an object is measured from the parallax based on the principle of the triangulation. In the camera using the imaging plane phase difference method, each pixel of an image pickup device has two photoelectric conversion sections (photodiodes), for example. In the imaging plane phase difference method, while parallax between a pair of images is determined from electric signals (hereinafter referred to as “image signals”) converted from images (optical images) formed by light fluxes entering the respective photoelectric conversion sections, an object image is acquired by adding up the image signals of the photoelectric conversion sections.
On the other hand, in a case where the camera is applied to a moving object, downsizing and durability of the camera are required, and hence normally, the camera is not provided with an auto focus function, but focus of the camera is fixed, whereby an in-focus position is set in the center of a measurable distance range (hereinafter referred to as a “distance measurement range”).
However, since in the triangulation, the accuracy of measurement of distance (hereinafter referred to as the “ranging accuracy”) is reduced in proportion to approximately the square of a distance to an object, there is a fear that the ranging accuracy is lowered at a long distance end of the distance measurement range.